I have one in a 40 breeder and he is a happy fella. The filter is being driven by a power head so there is plenty of water flow but he can get out of the direct path of it when he's too close. The fish he is with are compatible so he gets to swim around in a large area. He is in with 5 platies, 6 corydoras and a few shrimp that he and some of my platies think are food. Now and then they will eat one.

i agree with everyone else. if he is the only betta in there, and the other fish aren't nippy or too flashy- and there isn't a strong current, then he would do fine, most likely.
make sure the temp matches....obviously, if your 10 fish were goldfish, that would be a little chilly for a betta.

Make sure there aren't any 'nippy' fish, as they will tear up his fins. Also, fish that are colorful and flashy (i've heard fancy guppies can be problematic this way) can be mistaken as bettas and attacked.

Good Luck! Jessupha lived in a 55, with a decent current for quite some time, and loved it. (until i put the background up- after a week of him constantly flaring at his reflection, i moved him.)